Really easy stock to use up fish trimmings and old vegetables, you can freeze the stock in ice cube trays, freezing it this way means you can defrost as little or as much as you need at a time.
Rinse the fish bones and trimmings of any blood. Chop the leeks roughly and place into a large heavy-bottomed saucepan.
Chop the fennel, carrots, garlic, shallots, leeks and Parsley, stalks and all roughly and add to the pan.
Pour in the white wine, then add enough cold water to cover the fish and vegetables about 1.5 litres
Place the saucepan onto a high heat and bring the liquid to a simmer. After a few minutes, remove the scum that forms on the surface with a spoon or ladel. Reduce the heat and simmer for 20 minutes, skimming as needed
Remove the stock from the heat and strain, discarding the fish trimmings and the vegetables,
Cool and store in the fridge for up to three days or freeze. or you can reduce the stock further and then freeze it in ice cube trays.